1. Field of the Invention
The present invention relates generally to wheel locking devices. More particularly, the invention concerns a locking device for locking turn wheels of the type used on vehicles such as grocery shopping carts in a manner such that the turn wheel is releasably locked in a vehicle turning configuration.
2. Discussion of the Invention
Turning wheels are widely used in connection with various types of push carts, including grocery carts. The turn wheels, which are typically swivelly mounted proximate the front of the cart frame, function to facilitate turning and easy maneuvering of the cart. More particularly, the typical grocery cart includes a pair of rear wheels mounted for rotation on the rear of the cart frame, typically at laterally opposite sides of the cart. Similarly, the laterally spaced front turn wheels of the carts are mounted for rotation on either side of the frame for rotation about both horizontal and vertical axis.
Retail outlets such as grocery stores, shopping malls, hardware stores and garden centers generally use large numbers of shopping carts to facilitate handling and transport of goods by customers to and from check out points and to parked vehicles. Since these carts are typically subjected to rough handling by the customers, they are durably made of relatively expensive materials such as stainless steel, chrome steel and the like and each cart may cost $150.00 or more.
Because of the very large number of carts used in a single area, such as a shopping mall, and because of the large volume of business that is conducted in these areas, it is usually a very simple matter for a customer to remove a cart from the premises without being detected. In fact, the large number of carts misappropriated each year represents a significant factor in the overhead of those retail outlets which own the carts.
By way of example, in California alone, the Grocers Association estimates that some 750,000 carts are loose on California streets at any given time. Statistics show that losses due to cart misappropriation costs grocery stores alone about $17 million a year. The carts may be taken by customers who use them to wheel their purchases home, or to remotely parked vehicles and then fail to return them, or they may be misappropriated by vagrants who use them to hold and transport their possessions. The problem has become so serious in recent years that businesses have been created expressly for locating, retrieving and returning shopping carts that have been removed from retail establishments.
Because of the substantial problems involved in the misappropriation of grocery carts and similar shopping carts, a number of cart theft prevention systems have been suggested. A typical prior art anti-theft system comprises a lock out system which causes the carts to be immobilized when the carts pass a predetermined parameter relative to the retail establishment. These types of systems typically require that a usually quite complex and expensive brake lock or other immobilizing device be attached to, or built into the cart. Exemplary of such a prior art system is that described in U.S. Pat. No. 5,194,844 issued to Zelda. This patent discloses a theft prevention system for vehicles such as shopping carts, which are intended to be used within a prescribed area. The system includes a current conductor that circumscribes the prescribed area and each vehicle is equipped with a receiver circuit for operating a wheel lock mechanism when the vehicle moves out of the prescribed area. A somewhat similar prior art system is disclosed in U.S. Pat. No. 5,357,182 issued to Wolfe et. al.
Other more recent prior art security systems comprise the so called "Kart Control" system which is available from Controldyne Systems Inc. of Huntington Beach, Calif. and the Kart Saver System available from K-Lock and K-Alert Systems of Fairfield, Calif.
A common draw back of the prior art systems is the fact that the systems tend to be complex in construction and operation and most include large numbers of somewhat costly components which cause the systems to be expensive to manufacture. Further, the prior art systems tend to be generally unreliable in use and many are quite vulnerable to inclement weather conditions. Additionally, a number of the prior art systems are bulky, unattractive and can be hazardous in use. In this regard, certain of the prior art systems, which include an automatically actuated braking mechanism can cause the cart to come to an abrupt stop thereby subjecting the person pushing the cart to possible impact injury.
Another drawback of certain prior art wheel braking systems resides in the fact that, after the wheel is locked, the user of the cart will continue to push the cart even though one or more wheels may not rotate. This undesirably causes substantial damage to the locked wheel and frequently results in tread flattening which necessitates the costly replacement of the wheel.
As will become apparent from the description which follows, the novel wheel locking system of this present invention overcomes most of the drawbacks of the prior art systems and provides an elegantly simple and highly effective locking system which is easy to install and safe to use.